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Stars
The Alpha Centauri A and B pair offer a unique possibility to study
stellar physics in stars that are only slightly different from our own Sun. Their masses nicely bracket that of their neighbor star, the red dwarf Proxima, and they are only slightly older than the Sun. In addition to providing general information about stellar evolution, the detailed study of Alpha Centauri A and B is particularly interesting as it allows verification of our current knowledge about the composition, structure and indeed, future development, of our own main energy source, the Sun. An amber alpha star international group of astronomers has now used observations of Alpha Centauri A and Alpha Centauri B obtained with the ESO VLTI/Paranal team by the ESO VLTI to measure the sizes of these two stars. Despite their proximity and brightness, these two southern stars have never before been resolved by long-baseline stellar interferometry, and the VINCI/VLTI observations are the first direct measurement of their angular diameters. For the observations of the A and B pair, the 0.35-m VLTI siderostats on the observing platform at the Paranal summit. These two small test telescopes were placed at distances of 16 and 66 m, respectively. They captured the light from the two stars and sent it on via a series of reflecting mirrors to the common focus in the commissioning amber alpha star instrument VINCI. Although they were obtained only a few days after the successful accomplishment of "First Fringes" with the VLTI, the 16-m measurements were amber alpha star found to be scientifically very useful and helped to improve the measurement of the angular diameter of Alpha Centauri A. The 66-m baseline measurements provided the most accurate values of "calibrated visibilities" -- from these, the angular diameters were then derived. |
#2
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Stars
In article ,
harlod caufield wrote: The Alpha Centauri A and B pair offer a unique possibility to study stellar physics in stars that are only slightly different from our own Sun. Their masses nicely bracket that of their neighbor star, the red dwarf Proxima, and they are only slightly older than the Sun. That sounds like a misstatement. I could believe that A and B's masses might bracket our Sun's mass, but surely Proxima Cen, being so dim, must be much less massive than any of the other three. In addition to providing general information about stellar evolution, the detailed study of Alpha Centauri A and B is particularly interesting as it allows verification of our current knowledge about the composition, structure and indeed, future development, of our own main energy source, the Sun. An amber alpha star international group of astronomers has now used observations of Alpha Centauri A and Alpha Centauri B obtained with the ESO VLTI/Paranal team by the ESO VLTI to measure the sizes of these two stars. Despite their proximity and brightness, these two southern stars have never before been resolved by long-baseline stellar interferometry, and the VINCI/VLTI observations are the first direct measurement of their angular diameters. For the observations of the A and B pair, the 0.35-m VLTI siderostats on the observing platform at the Paranal summit. These two small test telescopes were placed at distances of 16 and 66 m, respectively. They captured the light from the two stars and sent it on via a series of reflecting mirrors to the common focus in the commissioning amber alpha star instrument VINCI. Although they were obtained only a few days after the successful accomplishment of "First Fringes" with the VLTI, the 16-m measurements were amber alpha star found to be ? ? ? scientifically very useful and helped to improve the measurement of the angular diameter of Alpha Centauri A. The 66-m baseline measurements provided the most accurate values of "calibrated visibilities" -- from these, the angular diameters were then derived. Happy to hear about successes in interferometry... This looks like a snippet of a press release -- whose? And, what diameter did they find? And, what's that about "amber alpha star"? The sentence doesn't quite make sense there. ?zed Stuart |
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